At the lab were I usually get my blood tests done, there is a person of the same nationality as me. We have never been 'properly introduced'. The first time I went to the lab, this person overheard me speaking the language and immediately jumped into the conversation. Like when you travel abroad, and someone overhears you speaking the same language and they immediately feel an imaginary (yet hardly real...) connection. They feel you share something, although you are complete strangers. They want to establish rapport, although given the same situation in your own country, they'd never approach you.
But how can you tell such persons you are really not interested in establishing rapport just because you happen to speak the same language... After all, you so happen to speak this language with some other 29 million people but you do not have a relationship with each and every one of them. Frankly, you probably don't even want that.
Yet, when someone tries to be nice, regardless of the reason, it's hard to be rude. Hard to tell them: You know what, I don't know you and frankly, I'm not really interested in knowing you just because we speak the same language, have the same skin color or drive the same car. How can you tell them that in fact, what drives them to approach you is annoying and offending, because it discriminates? Because it identifies you a priori with something you may not be, feel, share or want? Because it categorizes people, and you don't support that?
Funny thing is, every time this person realizes we speak the same language, they try to be extra kind, to serve us first, to bypass the lineup. All just because we happen to speak the same language. I know this seems insignificant, but let me assure you it is not. It is at the root of many discriminatory practices; and with time, such practices became institutionalized networks of influence and distribution of resources. Their discriminatory core becomes obscured; all it's left is the result: discrimination.